DUI checkpoints are one of the few circumstances where law enforcement officers are permitted to stop you, even if they have no reasonable suspicion to do so. Although this appears to be a serious violation of an individual’s 4th Amendment Constitutional rights, which protects people from invasion of privacy by government officials, checkpoints are permitted based on the rationale that it is considered a minor intrusion on privacy to stop someone quickly and it serves a substantial public benefit to deter drunk drivers. Thus, officers are permitted to stop you at a checkpoint for no reason, and they are even supposed to use a “neutral formula,” or simply an arbitrary number in deciding which cars to pull over.
State and Federal Courts have found that the public benefit outweighs the inconvenience of the intrusion on someone in a checkpoint stop. However, the Courts have also found that in order to balance things out, law enforcement agencies must limit the intrusiveness by taking various measures to ensure the checkpoint is not overly burdensome and invasive on innocent people. Thus, certain steps are generally taken in most checkpoint locations, to ensure that the potential stops are Constitutional.
In the landmark case on this topic, Ingersoll v. Palmer, the California Supreme Court analyzed a checkpoint stop that was conducted by the Burlingame Police Department in 1984. In that checkpoint location, there were substantial signs that indicated a checkpoint was ahead, and permitted drivers to exit the street prior to the checkpoint. This was considered by the Court as a major factor that limited the intrusiveness of the checkpoint stop. The primary purpose of the checkpoint location was to deter drunk drivers, not to simply catch drunk drivers. This was emphasized by the Court in their decision, and must be followed in California State Courts today.